Paint supply system



Feb. 20, 1951 F. E. wlLLIsoN 2,542,855

PAINT SUPPLY SYSTEM Filed May 25, 1946 2 Sheets-Sheet l m N a n W M I: Il! ulx'j 5 :am k* :11" ks H5' S 'H W w a 1* n Us m n H Si s m H H T n 2 1 R N m a s n n H' l gjm/UWM ff-T. DVD E. W/L/SO/V,

Feb. 20, 1951 F. E. wlLLlsoN 2,542,855

PAINT SUPPLY SYSTEM Filed May 25, 194e 2 sheets-sheet 2 GMW Patented Feb. 20, 1951 PAINT SUPPLY SYSTEM Floyd E. Willison, Middle River, Md., assignor to The Glenn L. Martin Company, Middle River, Md., a corporation of Maryland Application May 25, 1946, Serial No. 672,227

9 Claims.

My invention relates to an improved liquid circulating system and more particularly to a closed pressure system in which paint, lacquer, or like fluids, can be kept constantly agitated Without the use of a circulating pump.

It is customary practice in the operation of a supply system for paint spray guns to provide a mechanically operated circulating and mixing pump so as to assure a steady flow of fresh paint to the point where it is picked up for use by the gun. Such a system serves a number of useful purposes in that it overcomes the natural tendency of the heavy paint pigments to settle as well as to prevent clogging of the lines which would result if the paint is not circulated. However, one of the problems presented and remaining unsolved by the prior art is that of providing a circulating system capable of satisfactorily circulating paints containing high abrasive materials such as zinc chromate. Paints of this type, known as abrasive paints, have a wide field of application as protective coatings for various metals, but they are so highly abrasive as to quickly Wear away and render useless the ordinary system equipped with a circulating pump.

The present invention comprises a supply line adapted to supply paint, or like uid, to one or more spray guns from sealed storage tanks interconnected with a pressure line control means capable of regulating the pressure in the storage tanks to cause liquid stored therein to flow to and fro through the supply line under constant agitation without exposure to the air or any of the moving parts.

It is among the objects of this invention to provide a liquid supply system in which a liquid is maintained in motion by being automatically forced through a connecting supply line alternately from one storage tank to another.

An object of this invention is to provide a fluid circulating system extremely simple and highly efficient in operation capable of delivering a supply of fluid to a given point as a constantly moving body.

Another object of this invention is to provide a circulating system by which a iluid can be maintained in motion at a predetermined pressure.

A still further object of this invention is to provide a circulating system for use in connection with spray guns in which an air pressure is utilized to constantly agtate the paint by causing it to automatically flow from one storage tank to another thereby preventing the paint from settling and forming into a thickened mass.

Other objects of this invention will become ap- 2 parent from the following description when taken in conjunction with the drawings in which like numerals refer to like parts in different views.

In the drawings:

Figure 1 is a diagrammatic view of the circulating and agitating system of this invention.

Figure 2 is an enlarged sectional view of one of the pressure operated control switches.

Figure 3 is an enlarged view of the solenoid operated pressure air valve.

Referring in detail to the drawings, Figure 1 illustrates the system of this invention in which sealed storage tanks I9 and Il are interconnected by means of a gun supply duct I2. rllhe supply duct I2 is positioned and adapted to be tapped at one or more convenient points by tap fittings I3 supplied with shut-off valves I4 through which connecting hoses l5 supply paint, or like fluid, to the gun I9. The gun I6 is operated by air furnished through air supply line I'I connected to any convenient air supply (not shown).

Suitable sealable openings 59 are provided in the tops of the tanks I0 and |I for the introduction of the paint to be sprayed. The ends I8 of supply duct I2 are arranged to extend substantially to the bottom of each of the respective tanks with outlets I9 and 45 adapted for removal of the paint as it is forced thereinto under pressure.

Pressure is imposed upon the paint 20 to force it through duct I2 by air introduced into the top of tank IIJ through air iiow duct 2|. Air to operate the system is supplied from a convenient pressure source to air line 22 connecting with a four-way solenoid operated control valve 23 of conventional design. As shown in Figure 1, the solenoid actuated arm 24 of valve 231 has been moved to an extreme left position with passage 25 in the rotor 2'6 connecting air line 22 with an intervening nipple 2l that extends from the valve 23 to a T tting 28. The T tting 28 provides a take-off source for a pressure line 29 which terminates in chamber 30 of the pressure actuated switch 3| (Figure 2). Switch 3|, as shown in detail in Figure 2, is formed With two counterpoised bellows 32 and 33 formed with closed cavities as chamber 30 connecting with the pressure line 29 and a second chamber 34 connecting with a tube 35 that provides a passage leading into the bottom of tank I0. The arrangement of the pressure line 29 connecting chamber 3l] with the air flow duct 2| and tube 35 connecting the second chamber 34 with the interior of tank |0 is such as to allow for equalization of the pressures in chambers 39 and 34 except for the additional pressure in the second chamber 34 caused by the static head of paint 2li in the tank. It is obvious that this difference in pressure will be gradually reduced as paint 2li is forced out of tank l5 through supply duct l2 to the gun i6 with the unused paint flowing into tank l I.

The bellows 32 and 33 are separated by a bellows plate 35 hinged at one end 3l to the housing of ,switch 3l with the opp'bsite end A38 posi-y tioned to bear against a spring contact 39 capable of being moved into contact with an adjustable contact l so as to complete the electrical circuit through the switch between wires 4I. "Ih'es'etwo pressure of the air supply line.V The pressure exerted upon bellows 33 by the fluid in chamber 34 connected by tube 35 with the interior of the bottomY of tank l0 is equal to the static head of paint 2li in the tank plus the air pressure impressed upon `the `top of paint introduced through air inlet li2 of duct 2i. This pressure is suicient over Athe resultant range of pressure established between a full tank Vand an Aempty tank to expand bellows V33 -inoving plate y56 away from springcontact Y35 causing -the circuit between Wires ll to be broken. As the paint 25 -is removed from tank 1E, pressure on bellows 33 will be decreased with respect to the air pressure in chamber 30 of Abellows 32 and the tendency of the bellows '33 and 32 is to assumetheir balvaried.

` -When operated-normally with paint 25 being forced through duct T2 into vthe second tank I I,

rthe air remaining 'in the secondtank il is allowed to escape back through the air inletll of line 49 anda second nipple 56. Arrangement is 'made for this escapag'eof airby the provision "of 'a 'relief 'valve "4B of conventional design adjacent the control 'Valve'23`and connecting with -passage lll therein through a duct "58. -I, have "fon'cl'i't highlyde's'irable'to use a relief valve inV which the "pressure relief setting may be varied 1to compensate ff or variations in 'the bellows construction and'electric switch adjustment. 'Asecond ta'nk 'll is Ysimilarly 'equipped with an air'inlet lili by which air under 'pressure may be introduced into the top 'of 'tank Il, so as fto force the :excess paint notl used by theispray a'pertured'end #l5 spaced upwardlyfrom'the bot- Ltcmcf tank H. ed sw'itch'52, 'identical in"con'struction with 'switch 3l,is`position'ed adjacent the "bottom of tank Il "with Va conduit leading 'from the "bottom `of tank'll into the'b'ellows `o'fth'e switch.

Rotation "of the controlvalve 2'3 .is -attained by the Varrangement of a 'conventional double'acting solenoid i'n' which two field co'ils'are'positione'd f'op-posite e'ach other to act upon and v'motivate v `^"an --'a'rr`r1at11re 54 'as each eld coil vris respectively energized by an electrical current.` Arm 24 of the control valve 23 is suitably attached to armature 54 so that as the armature is drawn within the left coil 55 arm 24 is moved to the left, to assume the position shown in Figure l, and vice versa as the armature 54 is drawn within the right coil .55 the varm willfbe moved :to the right.

Thefsolenoid poils 55 Sand 55 are energized-by electrical energy supplied from any suitable -source connected to feed circuit 51 equipped with Va disconnect switch 58 for disconnecting the systemwhnnot in operation. As shown in Figure the electrical Icircuit to the control switches land solen'oid :coils .'is such that with disconnect Y tank Il will energize the left solenoid coil 55 and the alternate'closing of switch 3| adjacent tank l-B will energize the right coil 56.

When ready for operation, the right storage tank is .filled with paint Y2li -to ya predetermined flevel. The rstatic vhead Yof this lpaint, plus the vair pressure.thereaboveyisgsuch as to Vplace sufli- ;cient pressure -upon bellows .33 of switch 3| .to

cause expansion thereof, whichexpansion acts .to

open contacts 39-and bvmovementof plate'38 free of paint .presents a .balanced condition 'to the switch .52 so .as to -maintain a' neutral attitude with its plate '36 'bearing .against contact 35 tohold the .solenoid `55 fand the valve 4in 'full line position shown.

Operation of .the system is as `follows: "The electr-ical rcircuit 5'1 -is .energized 'by the closing of disconnect .su/'itch '58. The controlfswitch 52, being in `a closed position, v`permits electricity 'to Aflow vthrough and energize left solenoid coil which Aacts to rotate .rotor 325 of the air control valve 23 to the :position v.shown in Figure vl'with yportr25 aligned with air line "22 andpassage .in

nipple?, .and opposite passage '41 aligned .with

the passage Ain the.second .nipple'5'El and duct 48 connecting lwith relief valve '45. Air underpressure is then'introduced into air' line -22 to be directed through .control valve "23 and :air fl-ow duct '2i ninto the top of Atark lil. 'This .pressure must be sufficient .to l.force Ypaint 25 "upward `through-'duct I"2.to supplya gun f 6 at apressure conventionalto spraygunoperation. The diameter lof 'the rpipe f2 s proportional with respect to the demand of 'the spray ,guns so 'that the y supply'through l2 exceeds the gun demand and the surplusflows into the secondltank l l. An air .pressure line T25 .taken .o`fftheV air "flow duct .2|

and -terminated 'in `bellows 32 of switch BI 'is Y utilize'd -as a counterbalancing'force against any excessive pressure that might otherwisebe .developed inthe opposed bellows-"53 connected by tube 35 to the interior of'tankfill. Duringperiods of finoperation, or`i'f for any reason air lpressure in *"'to'oailsethe bellows'ito assume a neutral. positionwherebyplate 35 moves 'contact'39`into engagement with point Il@ .closing vthis electrical ci'rc'uitto'energize Vright solenoid'll. `qI'lie static head of the paint accumulated in the second tank li, plus the air pressure maintained by the relief valve is effective to cause switch 52 to open, deenergizing the left hand solenoid coil 55, The right hand coil t pulls armature 54 t0 the right rotating valve 23 to move passage 4l into registration with the air line 22 and the passage leading through sec-end nipple 50 and second line 49 into the second tank Il. Air thus admitted into tank H will force paint 2d therein back through supply duct i2 returning any unused portion thereof into the rst tank Hi. Such rotative movement of the valve 23 brings passage 25 into registration with the passages in nipple 21 and duct :i8 allownCr for escapage of the air in tank lil displaced therefrom as the level of paint in tank lil rises. rIhese reoccurring cycles of operation will automatically continue with a change of direction or air iiow from one tank to the other determined by the pressure on the pressure responsive control switches placed at the base of each storage tank in the system until substantially `all of the paint has been removed by the spray guns. Thus, as long as there remains a sunicient amount of paint in the system to unbalance the control switches, paint will be forced to now to and fro through the supply line in an agitated condition for use at the guns. By use of the term substantially all of the paint is meant all of the paint in the tanks except for that quantity remaining in the tank below the level of the outlets I9 and 45 spaced from the bottom of each respective tank a suincient distance to allow for the free passage of fluid into said outlets. Test means for determining the paint level in the tanks is provided for by installation of conventional pet cocks 6l in the sides of the tanks at dierent elevations, as shown in Figure l. In working operation with the system supplying paint to the spray guns located a considerable distance from the tanks, or at a substantially greater elevation above the tanks, the operating pressure must necessarily be increased in accordance with the lift and friction requirements of the system. However, I have found that with the conventional lay-out with a relatively short supply line that fifteen pounds pressure at the tanks is suiiicient and that the control switches unbalance to cause reverse iio-w of the paint at a pressure differential between the bellows of a iracticnor a pound. Such a system assures that the agitated paint will be constantly moved past the spray gun taps providing paint in satisfactory condition for use. By utilizing air under pressure over the liquid surface in the tank as a fluid moving medium the instant invention eliminates revolving or reciprocating pump parts, or sliding surfaces, that would be rapidly worn out by the abrasive pigments carried by the paint.

The arrangement of cut-off valves 62 in the spray duct i2 between each tank I0 and l I and the spray gun supply taps I3 provides for operation of the system as a standard pressure line spray gun supply system in case it may be desirable to replenish the Huid supply Without shutting down the guns. Such simplication of operation is attained by closing the shut-oi valve 62 between the tank to be refilled and the spray gun tap so as to remove this tank from pressure operation and by deenergizing the control switches to avoid automatic operation of the system during refilling. With the system in this condition, the closure of the empty tank opening 59 may be readily removed.k for the admission of an additional supply of fluid after which reclosure of the tank, opening of the shut-01T valve in the supply duct, `and reenergization of the control switches will again return the system to automatic operation, while in the meantime permitting air pressure to be maintained in the other tank to force a supply of fluid to the spray gun I6.

While I have described my invention in detail in its preferred embodiment, it will be obvious to those skilled in the art after understanding my invention that various changes, alterations, modications and substitutions can be made therein without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A liquid handling system comprising two tanks, a connecting liquid supply duct with ends terminating near the bottom of each tank, an air pressure inlet into each tank, a source of air pressure, a vent means to atmosphere associated with the inlet to each tank, a diverter valve having opposed passages adapted to alternately connect said air pressure inlets with the source oi air pressure and the vent means to lead air pressure into one tank and at the same time vent the other tank, and switch means responsive to a low liquid level condition in each tank connected to a source of electrical supply, a power `means associated with said switch means and operatively connected to the diverter valve for movement cr said diverter valve to vent the tank having a low level condition and direct air into the opposite tank.

2. A liquid handling system comprising two supply tanks, a connecting liquid supply duct with ends terminating near the bottom of each tank, an airpressure supply, an air pressure inlet into the top of each tank, a vent means to atmosphere associated with each tank, a diverter valve formed with passages adapted for alternate connection of said inlets with the air supply and said vent means to lead air .pressure into one tank and at the same time vent the other tank, switch means energized from a source of electrical supply and disposed for actuation in resp-onse to a low liquid level condition in each tank., solenoid means operatively connected to the diverter valve and electrically connected in circuit with said switches to operate said diverter valve to successively lead air into each tank to force a liquid from said tank through the duct connecting the tanks with the other tank vented to atmosphere.

3. A liquid handling system comprising two tanks adapted for pressurized operation, a connecting liquid duct with ends terminating near i the bottom of each tank, air pressure supply lines leading into said tanks, a source of air supply under pressure, a control valve associated. with the supply lines and said air source having a vent to atmosphere and passages disposed for connection with said lines and adapted to alternately direct said air under pressure into each tank and at the same time vent the other tank, valve actuating means having switches in an electrical supply circuit operative in response to a low liquid level condition in each tank and power means associated with the switches and supply circuit operatively connected t0 the control valve and adapted to operate said control valve to. direct air pressure into one tank at a time to force the liquid contained therein through the connecting duct with said other tank vented to atmosphere.

4. A liquid handling system comprising a plurality of closed tanks, a connecting liquid supply duct with ends terminating near the bottom of each tank, an air pressure inlet into each tank,

`a control lvalvefconnected between said .iinletsland asource of ua'ir supply lunder -pressure having .passages positioned to selectivelyfdirect air pressure into. said tanks `to force .the .liquid therefrom, :a vent :means associated .with the control valve adapted to release yairdisplaced by imovementiof said liquid v.into :each tank, rand aswitch means .of i an `electrical circuit responsive .to :a .low :liquid ilevelcondition in .each tank, and:solenoid means disposed 4tor energization fromsaidlelectrical cir- :Cuitloperatively .connected .to a xcontrolvalve.

k5. .-A Lpressurizedipaint.supply system comprising two supply tanks .connected :with :agsupply duct opening into said tanks, afsprayrgun with Vsupply .means connected :to .said iduct, the `supply .duct .being .dimensioned :to .provide .'ow .capacity .in excess .of the gun supply requirements, ,an Vr.air pressure supply line with inlets .leading into the vtop of .each tank, .an .electrical supply circuit, an

electrically actuated .control valve -connected.

with said circuit having .passages disposed .for

.communication between the airisupplyiandsaid inletsito selectivelyvdirect air;fr.omsaid aISuP-ply .line under 4pressure into :either .-tank to torce .the supply .of .paint contained therein `through 'the supply duct, ventlneans Vassociated'with said control valve having Va nassageto Aatmosphereadapt- `ed for communication ,with .the .other tank for y venting of .air .displaced by the excess '.paint deposited therein from said supply gduct, .switch means responsive to 'a low :level ..o'f the paint in either tank connected to selectively energize .the Y.eiectrically actuated .control valve to freverse the Adirect'nonof air .flow into .and out .of :the respecltive tanks iorrautomatic alternategremoval o fithe =to:at1nosphere, .andmpassages .disposed for Selei ely connecting-either :of said .inlets to Vsaid pressure supply .and 'the other of -said inlets .to .the entto lead airinto one-oi said tanks while providing .vent means :for the other tank, an nelectrical .sunply circuit, a Vpair .of electrical .switches .connected to said supply circuit having pressure rchambers .communicating .with the :interior oi each .tank and adapted to 'close the contacts .of the :switch (of .either tank :on .a -drop .of :pressure therein below a predetermined -value .due to ythe .removal V.of paint from said .tank :to energize the 'control value and effect movement .i ereef to direct .-a new .o vair tinto :the other .of .said tanks wher-relay `to alternately ,reverse the new of the paint through said vsupply'".duct.

57.. Apnessurizedpaint supply system .compris- Isupply tanks, a connecting :liquid 'supuct with :onen ends :terminating near ithe n fof .each tank, :spray gun lsupply Ymeans :connesting with said ;duct, air pressure inlets into feach tank, 4:an Yair .pressure supply line, za

:control valve :connected with the .Lai-r supply .iine fha-ving .passages .adapted for lconimunication the `tween 'the air .inlets .and -said fair .supply and ithe atmosphere .to .selectively ldirect 'air :pressure lthrough the ipressure .inlet to either tank andrat the .same time vent ithe Lin'letof lthe other tank, ran electrical :supply .-circuit, fa "valve 'actuating' ameans connected to said .electrical eupllly cir- =cu`it `,'rvith Iswitch means .responsive 'to .the quarritity :of .paint .in .each tank, said switch r`means 7h9- iing arranged ato energize :said Naive .actuating -rneans upon `:removal of substantially :allro .the .paint :from 'the tank vunder pressure .to cause-said :valve to direct lair ,into the other vtankaand went :the irst atank to atmosphere.

8. .n pressurized paint supply system 'comprising ztwo .supply tanks, :a rconnecting liquid supply :duct having ,spray .gun :tap :points :spaced from .thefopen endsof said .duet with one of saidfends Ipositioned in :each ,tank :to receive vand nouvey Epaint :between said tanks, yan .air `inlet into reaclflV tan-k, :an .air pressure fsupp'ly, .a diverter valve .having :a Yplurality .of .passages -xiisposed to .selectively rdirect air .under pressure .into one of -said .tanks :andat the same .time vent .the :other tank, .a source or .electrical `power esupply .and power. means connected in circuit .with sw-itch .ni-Gans responsive to aflow liduidlevel condition in either tan-k 'operativelyconnectedztozthe divertter .value -to=operate said .valve to dirent air iirrto .the 1opposite tankaand at zthefsame time 'vent .tank .previously :communicating f with said :air pressure supply.

:9. A 'liquid .agitating system fcomprising a :plurality of tanks connected lwith a liquid supply duct having openings spa-cedirom .the ibottomiof reach ytank, a `*source .02E .air 'under pressure, .air

r`.ducts having vnnen sends opening A'into .each :of

.said 7 tank-s, -a -valve vmea-ns having passages adapted for movement into communication between said Lair-:source rand ,said air ducts to selectively :direct .air into Y'certain .of said tanks, :vent .means controlled by said valve :disposed for selective connection with fsaid .air .ducts Ito :at .the same :time :vent the tether .of .fsaid .tanks to atmosphere, :afsource of electrical supply, .anfelectrical power I .REFERENCES oITED The following references are `of record Vin the Y "le Pof I'this jpat'ent:

UNITED .STATES PATENTS eNumlcer Name Date 649,803 Brock et al :May 15, 119.00 x3925,0il2 Moore .June I5, -1909 annata@ :Garrisonet a1. June 11o, `194.1 

